In many countries operators and Internet service providers are today obliged by legal requirements to provide stored traffic data generated from public telecommunications and Internet services for the purpose of detection, investigation and prosecution of crime and criminal offences, including terrorism.
Usually a public official, for instance a judge, is in charge of authorizing investigation on target persons, allowing to activate lawful interception on their communications or to query on data retention databases. The authorization paper is conventionally referred to as a “warrant”, which is provided to lawful enforcement agencies.
According to a received warrant, the lawful enforcement agency (LEA) may set targets of interception and/or query data retention databases.
Messages that are object of interception or retention are managed through an architecture, referred to as messaging architecture, that allows users to exchange information irrespectively of the underlying technology and/or of the recipient's capabilities.
Such architecture may comprise a plurality of messaging servers, a dispatcher and a message store. Each server may be specific to a kind of application, for instance SMS, MMS, voice-mail, email, and so on. The dispatcher is in charge of routing information by selecting which messaging server should be used to deliver a message, according to recipient's preferences or capabilities. The message store may be a file server configured to temporarily host user messages, for instance through a mailbox folder.
This kind of architecture allows messages to flow transparently from the sender to the receiver, even if the receiver is not able to receive the original message in the format intended by the sender. For instance, the original message may be an MMS message directed to a recipient that is not able to receive MMS messages but, for example, only SMS messages.
In that case, the dispatcher may check the recipient's capabilities and may direct the SMS messaging server to convert the original MMS message into an SMS message, so that a message, though in converted form, can be delivered to the recipient.
A conventional architecture for Lawful Interception (LI) comprises an Intercepting Control Element (ICE) providing the user equipment of the target user with an access to the telecommunications network
Problems with existing solutions occur when, as in the above example, a message must be converted and/or stripped of part of its content, such as when an MMS is converted into an SMS, to be delivered to the recipient.
If the recipient is the target user of a Lawful Interception system, the original message may contain richer information than it is contained in the converted message, which converted message, in current systems, represents the object of interception.
It would be desirable not to lose the richer information contained in the original message, which could be relevant for lawful interception purposes.